1. Field of the Disclosure
The present disclosure relates to sensor modules each having a side-by-side structure or a chip stack structure and a sensor chip and a processing circuit chip used therefor.
2. Description of the Related Art
By using various kinds of sensors, a motion of a user or a state of a device used by the user is sensed and is used for controlling the device.
Usually, such sensors each have one molded package, in which a sensor chip and a processing circuit chip are housed, and are each provided as a sensor module made operable by connecting a power supply and a minimum number of pins therewith. While needless to say, a sensor chip and a processing circuit chip are separately molded and are connected on a printed wiring substrate by a user, thereby enabling each of such sensor modules to be realized, it is necessary to connect pins extending from the molded sensor chip and pins extending from the molded processing circuit chip with each other, thereby causing a size to be enlarged and badly influencing aspects of performance and reliability. A sensor chip and a processing circuit chip tend to be housed in one molded package, thereby making a small-sized, high-performance, and high-quality sensor module available for various purposes.
While there are various methods for housing, in one molded package, and connecting a sensor chip and a processing circuit chip with each other, there is a method for establishing connections by using wire bonding, as one of methods technologically established with low costs. Usually, it is difficult for the wire bonding to establish connections that intersect with each other. Therefore, it is necessary to decide the pad arrangements of a sensor chip and a processing circuit chip and the alignment orders thereof. Regarding the arrangement of a sensor chip and a processing circuit chip in a sensor module housed in a molded package, a side-by-side structure in which the two are arranged on a plane surface and a chip stack structure in which one of the two is stacked on the other are known as typical examples.
In, for example, Japanese Unexamined Patent Application Publication No. 2009-270905, a sensor device having the side-by-side structure is disclosed. FIG. 18 is an explanatory diagram of a sensor unit arranged in a sensor device 100 of Japanese Unexamined Patent Application Publication No. 2009-270905.
A sensor chip 110 and a processing circuit chip 120 are mounted in a leading end portion of a projecting portion 102 of a case 103 and are connected by bonding wires 111. Since being relatively easily manufactured, the side-by-side structure in which the sensor chip 110 and the processing circuit chip 120, two-dimensionally arranged, are connected by the bonding wires 111 is widely used in sensor modules each having little restriction on the size thereof.
However, in a case where, along with the recent miniaturization of sensor modules, it is necessary to reduce an area at the cost of a thickness, the chip stack structure in which the sensor chip is mounted on the processing circuit chip is used. In that case, while there is a method for translating and mounting the sensor chip on the processing circuit chip, this causes the bonding wires to pass through the upper portion of a detection unit of the sensor, thereby causing a problem on the detection accuracy of the sensor. In a case of rotating and mounting the sensor chip on the processing circuit chip in order to avoid the above-mentioned problem, the arrangement of the sensor chip and the processing circuit chip and the orders of the respective pad arrangements thereof become unmatched to each other. Accordingly, it is necessary to change the arrangement or order of pads of the sensor chip or the processing circuit chip and remanufacture from a chip, and there is a problem that a development cost is increased.